/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package cn.icanci.snow.spring.mvc;

import cn.icanci.snow.spring.aop.AspectWeaver;
import cn.icanci.snow.spring.core.BeanContainer;
import cn.icanci.snow.spring.exception.InitDispatcherServletException;
import cn.icanci.snow.spring.inject.DependencyInjector;
import cn.icanci.snow.spring.mvc.processor.RequestProcessor;
import cn.icanci.snow.spring.mvc.processor.impl.ControllerRequestProcessor;
import cn.icanci.snow.spring.mvc.processor.impl.JspRequestProcessor;
import cn.icanci.snow.spring.mvc.processor.impl.PreRequestProcessor;
import cn.icanci.snow.spring.mvc.processor.impl.StaticResourceRequestProcessor;
import cn.icanci.snow.spring.util.BeanUtil;
import lombok.extern.slf4j.Slf4j;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet 派发器
 *  - 拦截所有的请求
 *  - 解析请求
 *  - 派发请求
 *  
 * @author icanci
 * @date Created in 2021/05/19 17:19
 * @version 1.0
 */
@Slf4j
@WebServlet("/*")
public class DispatcherServlet extends HttpServlet {
    List<RequestProcessor> PROCESSOR = new ArrayList<>();

    @Override
    public void init() {
        try {
            // 1.初始化容器
            BeanContainer beanContainer = BeanContainer.getInstance();
            // 2.读取需要加载的包
            List<String> packages = BeanUtil.loadBeanPackages();
            beanContainer.loadBeansByPackages(packages);
            new AspectWeaver().doAop();
            new DependencyInjector().doIoc();
            // 3.初始化请求处理器责任链
            PROCESSOR.add(new PreRequestProcessor());
            PROCESSOR.add(new StaticResourceRequestProcessor(getServletContext()));
            PROCESSOR.add(new JspRequestProcessor(getServletContext()));
            PROCESSOR.add(new ControllerRequestProcessor());
        } catch (Exception e) {
            log.error("init error, message:{}", e.getMessage());
            throw new InitDispatcherServletException("DispatcherServlet init error", e);
        }
    }

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // 1.创建责任链对象实例
        RequestProcessorChain requestProcessorChain = new RequestProcessorChain(PROCESSOR.iterator(), req, resp);
        // 2.通过责任链模式来依次调用请求处理器对请求进行处理
        requestProcessorChain.doRequestProcessorChain();
        // 3.对处理结果进行渲染
        requestProcessorChain.doRender();
    }
}
